1. Field of the Invention
The present invention relates to an oscillatory mirror device suitable for use to oscillate light beams such as laser beams in a laser beam working.
2. Description of the Prior Art
As is disclosed in, for example, Japanese Patent Laid-open Publication 58-184080, the oscillatory mirror device for use in a laser working was conventionally generally constructed to comprise a mirror, a rotary shaft connected with the mirror to define an axis of oscillation of the mirror, a base structure for supporting the rotary shaft to oscillate about an axis of oscillation, and an exciting means engaging a portion of the mirror distant from the axis of oscillation.
In the above-mentioned conventional construction of the oscillatory mirror, the rotary shaft is exerted with side forces perpendicular to the longitudinal axis thereof due to the exciting forces applied to the mirror from the exciting means so that the rotary shaft exerts eccentric forces to the bearing means which support the shaft from the base structure, thereby causing an early wearing or failure of the bearing means, resulting in various troubles such as incorrect alignment of the laser beams, difficulty in maintaining high frequency of oscillation, undue vibrations of the mirror, high noise, etc.